Field of the Invention:
The invention concerns a chair, in particular an office chair, with a synchronous mechanism.
Modern, high-quality office chairs are typically provided with a synchronous mechanism that ensures that the seat moves synchronously with the backrest. The synchronous mechanism typically contains a seat support and a backrest support as well as sliding guides and/or rotary joint arrangements by which these two parts are connected with each other and with the seat and/or backrest. The synchronous mechanism is configured such that movement of the backrest also results in a change in the position of the seat. If the backrest is tilted, the seating area is also tilted backward and downward. Various configuration variants are available for the synchronous mechanism. Office chairs with synchronous mechanisms can be found, for example, in German patents DE 101 22 946 C1 or DE 101 22 948 C1 corresponding to U.S. Pat. Nos. 6,692,075 and 6,896,329, respectively.
In order to ensure a high level of comfort for the user of the chair, its mechanical properties, in particular the return force acting on the backrest, are adjusted depending on the weight of the user. If the same chair is used by different users of different weights, then a simple adjustment to the current weight in each case is desired. One possibility, for example, is to adjust the spring pretension of a return element using a manual adjustment mechanism.